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SEASONAL AFFECTIVE DISORDER (1)
Nita Bishop, Clinical Herbalist
Hippocrates believed that diseases are related to the seasons of the year, stating "Whoever wishes to pursue the science of medicine in a direct manner must first investigate the seasons of the year and what occurs in them." - Hippocrates
The cold, dark, damp and rainy, gray days are upon us. Lengthy periods of darkness are known to cause the winter blues and even more serious levels of depression. In psychiatric usage, mood disorders are referred to as affective disorders. One in twenty Americans may have some mood disorder during their lives which could develop into major long term depression. Consequently, the normal winter environment in many locations poses a greater challenge to such individuals.
The National Institute of Mental Health first identified "seasonal affective disorder," or SAD, in 1980. Today it is officially recognized by the medical and psychiatric communities as a subgroup of major depression and a mood disorder. One of the first people to bring SAD to national attention was Norman Rosenthal, MD, author of the newly revised "Winter Blues: Seasonal Affective DisorderãWhat It Is and How to Overcome It. " According to Dr. Rosenthal, "An estimated ten million Americans are said to be suffering from SAD, and another 14% of the adult U.S. population is estimated to suffer from...the winter blues."
SAD is also four times more common in women, than men; even children may sometimes be affected. Symptoms of sadness, fatigue, depression, diminished concentration, withdrawal, apathy, irritability, sleep disturbances (sleeping more and waking unrefreshed), decreased physical activity, weight gain, and increased appetite may begin gradu-ally during the winter months as the length of sunlight begins to diminish.
There are no clear cut treatments for SAD, mainly because not all of the symptoms occur for each depressed individual. In addition, there may be other causes for the depression that SAD may be exacerbating: hypothyroidism, hypoglycemia, chronic viral infections, and chronic fatigue syndrome. Although there are a multitude of other diseases that produce similar symptoms, the cyclical nature of this disorder is key to diagnosing SAD.
Biochemical Roots of SAD
Although SAD is now fully recognized as a valid disease, the phys-iologic pathways are still not well understood. There are no definitive tests to confirm SAD. It appears that these disorders are affected by biochemical disturbances involving the hormone melatonin and the neu-rotransmitter, serotonin. The subsystem involved in seasonal depression is the brain and the element for this illness is the hypothalamus. Anatomically, the most likely route along which photoperiodic informa-tion may be channeled is the retinohypothalamic tract that terminates in the hypothalamus. The hypothalamus controls emotion/mood, heat/ cold response, food, sex drive; it also controls the perception of light. Consequently, the decreased amount of sunlight during the winter is believed to be one of the etiological factors of SAD.
Another consideration is circadian rhythms, which are the body's natural cycles that control sleeping, wakefulness, and hormone secre-tion. Light exposure helps the body synchronize its "internal clock." There is some evidence that disturbed biological rhythms are a conse-quence of inconsistent resetting of the circadian pacemaker and these rhythms are worsened by shorter periods of daylight, exposure to cold weather, and aging.
Melatonin produced by the pineal gland regulates the circadian rhythms and the sleep-wake cycle. When there is no sunlight, melatonin is secreted. Increased melatonin levels in the body have been associated with increased drowsiness. This sets up a corresponding feedback loop since sleep can induce or reverse many of the functions of the hypothalamus.
In addition to melatonin, the pineal gland also produces the neurotransmitter serotonin, which produces a heightened sense of calm, lowering stress and anx-iety and inducing sleepiness. Serotonin is a derivative of tryptophan, an amino acid that is present at low levels in the bloodstream. During the short days of winter, this neurotransmitter reaches its lowest concentrations in key parts of the brain. The body produces less serotonin in winter, and low serotonin levels are believed to be one of the primary causes of clinical depression. Serotonin also inhibits the stress-induced increase of cortisol secretion and "stress" hormones. Cortisol has an inhibitory effect on the immune system, which could explain some of the physiological changes in depression.
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